1 A Review of Current Routing Protocols for Ad-Hoc Mobile Wireless Networks By Lei Chen

2 What is Ad Hoc Wireless Network? A collection of mobile nodes that are dynamically and aribitrarily located Infrastructureless mobile network Each node must act as a router Most nodes will not wish to perform any administrative actions to set up such a network.

3 Routing Protocols Ad-Hoc Routing Protocols Table Driven Source-initiated On-Demand Driven DSDV WRP AODV DSR TORA ABR SSR CGSR

4 Table Driven Routing Protocol Attempt to maintain consistent, up-to-date routing information from each node to every other node in the network The number of necessary routing-related tables and methods of broadcasting are different

5 Destination-Sequenced Distance- Vector Routing (DSDV) A table based protocol Every node maintains a complete table listed all possible destination Each entry of the table marked with a sequence number assigned by the destination node

6 DSDV (continue) Every node keep a route table for every possible destination

7 Source-initiated On-demand Routing Protocol Initiates a route discovery process within the network, when a node requires a route to a destination Maintain by some form of route maintenance procedure until either the destination becomes inaccessible or the route is not desired

8 Ad-hoc On-demand Distance Vector Routing (AODV) An on demand routing protocol Description AODV uses a broadcast route discovery mechanism as is also used in DSR. Instead of source routing, however, AODV relies on dynamically establishing route table entries at intermediate nodes

9 AODV (continue) A mobile node maintains a table entry for each destination of interest. Route table entry contains the following information: Destination Next Hop Number of hops (metric) Sequence number for the destination Active neighbors for this route Expiration time for the route table entry Source node sends a RREQ packet Intermediate nodes forward it to destination Destination node distinguish the RREQ by, and sends back RREP when receives the first RREQ packet.

10 Dynamic Source Routing (DSR) An on-demand routing protocol Description –A source flood REQUEST if it has data to send but no route to its destination is know –When the destination get the REQUEST, it sends a REPLY to the source via the recorded route –Use source routing instead of hop-to-hop routing

11 DSR continue Every node has a cache which contain the complete path information to the destination node If the source node cant find the destination node in its cache, it will initial a route discovery The source node sends the RREQ packet which is Intermediate node –If it is the destination copy the head and send RREP –If it is already listed in the route-record, discard it –Else, it forward the RREQ, and add itself in the route-record

12 Table-Driven vs On-Demand Routing Table-Driven –is similar to the connectionless approach of forwarding packets, with no regard to when and how frequent such routes are desired –A routing is always available, regardless whether or not it is needed On-Demand –Has to wait until a desired route is discovered.